Centrifugal air blower unit having movable portion

ABSTRACT

A centrifugal air blower unit includes a centrifugal multi-blade fan, a scroll casing, and an introduction duct. The fan has a rotation axis and a plurality of blades. The scroll casing provides a first air passage. The introduction duct provides a second air passage. The fan sucks the air from the rotation axis and blows the air toward the outer circumference of the fan. The first and second air passages flow the air blown from the fan. The inner wall of the introduction duct includes a movable portion. The inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion is displaced in accordance with the airflow amount of the air blown from the scroll casing.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based on Japanese Patent Application No. 2003-3273 filed on Jan. 9, 2003, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a centrifugal air blower unit having a movable portion, which is suitably applied for an air blower unit of an air conditioning apparatus.

BACKGROUND OF THE INVENTION

[0003] A conventional centrifugal air blower unit is disclosed and specifically described in Japanese Unexamined Patent Application Publication No. 2002-161896 and Japanese Examined Patent Application Publication No. H07-92079.

[0004] A scroll casing of the centrifugal air blower unit provides an air passage having a scroll shape (i.e., a convolution shape). The air passage is disposed on an outer circumference of a centrifugal multi-blade fan. A cross section of the air passage becomes gradually larger, as it goes from a nose (i.e., a volute tongue of the scroll casing) to an end of the scroll casing so that the air in the air passage is effectively congregated, and then the air is blown from the centrifugal multi-blade fan to the downstream side of the fan.

[0005] Therefore, the optimum dimensions of a figure size of the scroll casing is required to vary in relation to an amount of the air to be blown from the scroll casing. Specifically, an increasing rate of the cross section of the air passage (e.g., an expanding angle of the air passage) and the cross section of the air passage are changed in relation to the air-blow amount for optimizing them.

[0006] Therefore, in the prior art, the air blower unit includes a variable blade in the air passage, which has a scroll shape provided by the scroll casing. The variable blade moves toward a direction parallel to the rotation axis of the centrifugal multi-blade fan in relation to the air-blow amount so that the cross section of the air passage is changed.

[0007] Specifically, the air blower unit includes a door means 124 disposed near an air outlet of the scroll casing 172, as shown in FIG. 7. The door means 124 rotates around a rotation axis, which is parallel to the rotation axis of the centrifugal multi-blade fan 171. The door means 124 switches a door between opening and closing in relation to an operation mode. Specifically, the door means 124 optimizes the dimensions of the figure size of the scroll casing 172, i.e., the door means optimizes the dimensions of the air passage in relation to the air-blow amount.

[0008] In this case, the cross section of the air passage in the scroll casing 172 becomes much larger, just after the air passes through the door means 124. Therefore, a turbulence of the airflow, i.e., a vortex of the airflow is generated at the downstream side of the door means 124 in the airflow direction. That is because the air, which flows along with a sidewall of the door means 124 and the scroll casing 172 in a case where the door means 124 is opened, breaks away from the sidewall of the scroll casing 172 in a case where the door means 124 is closed. Thus, a noise generated by the vortex of the airflow becomes larger, and the air-blow amount of the air blowing from the air blower unit is decreased by a vortex loss of the vortex of the airflow.

SUMMARY OF THE INVENTION

[0009] In view of the above problem, it is an object of the present invention to provide a new centrifugal air blower unit. Specifically, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise.

[0010] A centrifugal air blower unit blows an air to a heat exchanger. The unit includes a centrifugal multi-blade fan, a scroll casing, and an introduction duct. The centrifugal multi-blade fan has a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan. The scroll casing accommodates the fan and provides a first air passage so as to flow the air by an air flow amount. The introduction duct has an inner wall and provides a second air passage. The fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan. The first air passage has a scroll shape and flows the air blown from the fan. The second air passage introduces the air blown from the scroll casing toward the heat exchanger. The inner wall of the introduction duct includes a movable portion. The inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion is displaced in accordance with the airflow amount of the air blown from the scroll casing.

[0011] In the above unit, both of the first and second air passages can be optimized in accordance with the airflow amount. Even when the movable portion is displaced, all circumference of the inner wall of the duct is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passages. Therefore, no vortex is generated in the duct. Thus, a noise generated by the vortex of the airflow is reduced, and the airflow amount of the air blowing from the airblower unit is prevented from decreasing. Here, the decreasing of the air-blow amount is caused by a vortex loss of the vortex of the airflow.

[0012] Thus, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise.

[0013] Further, a centrifugal air blower unit blows an air to a heat exchanger. The unit includes a centrifugal multi-blade fan, a scroll casing, and an introduction duct. The centrifugal multi-blade fan has a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan. The scroll casing with a nose accommodates the fan and provides a first air passage so as to flow the air by an airflow amount. The introduction duct has an inner wall and provides a second air passage. The fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan. The first air passage has a scroll shape and flows the air blown from the fan. The second air passage introduces the air blown from the scroll casing toward the heat exchanger. The inner wall of the introduction duct includes a movable portion, which connects to the nose of the scroll casing. The inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion of the inner wall of the introduction duct is displaced in accordance with the airflow amount of the air blown from the scroll casing.

[0014] In the above unit, both of the first and second air passages can be optimized in accordance with the airflow amount. No vortex is generated in the duct, so that the airflow amount of the air blowing from the air blower unit is prevented from decreasing. Thus, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise.

[0015] Further, a centrifugal air blower unit blows an air to a heat exchanger. The unit includes a centrifugal multi-blade fan, a scroll casing, and an introduction duct. The centrifugal multi-blade fan has a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan. The scroll casing with an outer periphery accommodates the fan and provides a first air passage so as to flow the air by an airflow amount. The introduction duct has an inner wall and provides a second air passage. The fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan. The first air passage has a scroll shape and flows the air blown from the fan. The second air passage introduces the air blown from the scroll casing toward the heat exchanger. The inner wall of the introduction duct includes a movable portion, which connects to the inner wall disposed at the outer periphery of the scroll casing. The inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion of the inner wall of the introduction duct is displaced in accordance with the airflow amount of the air blown from the scroll casing.

[0016] In the above unit, both of the first and second air passages can be optimized in accordance with the airflow amount. No vortex is generated in the duct, so that the airflow amount of the air blowing from the air blower unit is prevented from decreasing. Thus, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise.

[0017] Further, an air conditioning apparatus is suitably used for a passenger compartment of a vehicle. The apparatus includes a centrifugal air blower unit according to claim 1; a blower mode switching device for switching a blower mode of the air to be blown into the passenger compartment; and a controller. The controller controls the airflow amount of the air blowing from the scroll casing on the basis of an operating condition of the blower mode switching device.

[0018] In the above apparatus, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise, so that the apparatus is much improved.

[0019] Further, an automatically controlled air conditioning apparatus is suitably used for a passenger compartment of a vehicle. The apparatus includes a centrifugal air blower unit according to claim 1; and a controller for calculating a target temperature of the air to be blown into the compartment and for controlling at least one of a blower mode of the air to be blown into the passenger compartment and an airflow amount of the air blowing from the centrifugal air blower unit on the basis of the target temperature. The controller controls the airflow of the air blowing from the scroll casing on the basis of the target temperature. In the above apparatus, the centrifugal air blower unit has high air-blow efficiency and low air-blow noise, so that the apparatus is much improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

[0021]FIG. 1 is a schematic view showing an air conditioning apparatus, according to a first embodiment of the present invention;

[0022]FIG. 2 is a block diagram showing the air conditioning apparatus according to the first embodiment;

[0023]FIG. 3 is a schematic cross sectional view showing a centrifugal air blower unit according to the first embodiment;

[0024]FIG. 4 is a cross sectional view explaining an operation of the air blower unit according to the first embodiment;

[0025]FIG. 5 is a cross sectional view explaining the operation of the air blower unit according to the first embodiment;

[0026]FIG. 6 is a schematic cross sectional view showing a centrifugal air blower unit according to a second embodiment of the present invention; and

[0027]FIG. 7 is a schematic cross sectional view showing a centrifugal air blower unit according to a prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] (First Embodiment)

[0029] A centrifugal air blower unit according to a first embodiment of the present invention is suitably used for an air conditioning apparatus 1 of a vehicle, as shown in FIG. 1.

[0030] At the upstream side of an air conditioning casing 2 in the airflow direction of an airflow path, an inner-air inlet port 3, an outer-air inlet port 4 and an air-switching door 5 are disposed. The inner-air inlet port 3 sucks the inner air disposed in a passenger compartment of the vehicle. The outer-air inlet port 4 sucks the outer air disposed outside of the compartment. The inside/outside air-switching door 5 switches the inlet ports 3, 4. The air-switching door 5 is controlled (i.e., opened or closed) manually or by a servomotor or the like.

[0031] At the downstream side of the air-switching door 5, a filter (not shown) for filtering the air dusts and a centrifugal air blower unit 7 are disposed. The air is sucked by the air blower unit 7 through the inlet ports 3, 4, and then blown toward air outlets 14, 15, 17.

[0032] At the downstream side from the air blower unit 7, an evaporator 9 is disposed. The evaporator 9 is a cooling device for cooling the air to be blown into the passenger compartment. The air sent by the air blower unit 7 passes entirely through the evaporator 9. Here, the evaporator 9 is a low-pressure side heat exchanger in a vapor compression refrigerating system. The system cools the air by evaporating a refrigerant in the system.

[0033] At the downstream side from the evaporator 9, a heater 10 for heating the air to be blown into the passenger compartment is disposed. The heater 10 heats the air with using a coolant of an engine 11 (i.e., E/G) as a heat source.

[0034] A bypass passage 12 for bypassing the heater 10 is disposed in the air conditioning casing 2. An air mix door 13 is disposed at the upstream side from the heater 10. The air mix door 13 controls a ratio between the air passing through the heater 10 and the air passing through the bypass passage 12 so that the air mix door 13 controls the temperature of the air to be blown into the passenger compartment. At the downstream side of the air conditioning casing 2, air outlets 14, 15, 17 are disposed. The air outlet 14 works as a FACE outlet for blowing the air toward an upper side of the passenger compartment, so that the air blows toward an upper body of a passenger in the passenger compartment. That is called a face mode of the air conditioning apparatus. The air outlet 15 works as a FOOT outlet for blowing the air toward a lower side of the passenger compartment, so that the air blows toward a lower body of the passenger in the passenger compartment. That is called a foot mode of the air conditioning apparatus. The air outlet 15 works as a DEFROSTER outlet for blowing the air toward a window shield glass 16 (i.e., the inner surface of the glass 16) of the vehicle. That is called a defroster mode of the air conditioning apparatus.

[0035] Each outlet 14, 15, 17 has a blower mode switching door 18, 19, 20, respectively. The blower mode switching door 18, 19, 20 is disposed at the upstream side from the outlet 14, 15, 17. The blower mode switching door 18, 19, 20 controls and switches a blower mode among the face mode, the foot mode and the defroster mode. The blower mode switching door 18, 19, 20 is controlled manually or by a servomotor or the like.

[0036] Thus, the blower mode is composed of the face mode for blowing the air from the FACE outlet 14, the foot mode for blowing the air from the FOOT outlet 15, and the defroster mode for blowing the air from the DEFROSTER outlet 17. The blower mode further includes a bi-level mode for blowing the air from both of the FACE outlet 14 and the FOOT outlet 15, and so on.

[0037] In general, when the air conditioning apparatus 1 is operated in the FACE mode, it is required to have a large amount of the air-blow to be blown into the compartment. Therefore, the FACE outlet 14 is set to be parallel to the air passage of the air conditioning casing 2 so that a pressure loss (i.e., an airflow resistance of the air passage) in case of the FACE mode becomes smaller than that in case of the FOOT mode, the DEFROSTER mode and the like.

[0038] As shown in FIG. 2, several signals are inputted into an electronic control unit (i.e., ECU). The signals are a detection signals outputted from a plurality of air conditioning sensors 22 and a signal outputted from an operation panel 23. The detection signals are, for example, a detection signal from an outside air temperature sensor for detecting the temperature of the outside air outside the passenger compartment, a detection signal from an cooled air temperature sensor for detecting the temperature of the air just after passing through the evaporator 9, a detection signal from a solar radiation sensor for detecting an amount of solar radiation entered into the passenger compartment. The signal from the operation panel 23 disposed in the passenger compartment corresponds to a setting temperature, which is set by the passenger in the passenger compartment.

[0039] The ECU 21 calculates a target temperature TAO in accordance with a predetermined program on the basis of the above signals inputted into the ECU 21. The target temperature TAO is a target temperature of the air to be blown into the passenger compartment. Specifically, the target temperature TAO is calculated, and then the ECU 21 controls the air-switching door 5, the air mix door 13, the blower mode switching doors 18, 19, 20 and the air blower unit 7. Here, the ECU 21 controls the air blower unit 7 with an applied voltage applied to an electric motor (not shown) of the air blower unit 7, so that the airflow amount of the air blower unit 7 is controlled. The electric motor rotates the centrifugal multi-blade fan 71.

[0040] Next, the air blower unit 7 is described in detail as follows.

[0041] As shown in FIG. 3, the air blower unit 7 includes the centrifugal multi-blade fan 71, an electric fan motor (not shown), a scroll casing 72, a introduction duct 73 and the like. The fan 71 includes a plurality of blades 71 a, which is disposed around a rotation axis of the centrifugal multi-blade fan 71, so that the fan 71 sucks the air from the rotation axis, and blows the air toward the outer periphery of the fan 71. The fan motor works as a driving means for rotating the fan 71, and is disposed on one side of the rotation axis of the fan 71. The scroll casing 72 accommodates the fan 71, and provides an air passage 72 a having a scroll shape (i.e., a convolution shape). The air blown from the fan 71 flows in the air passage 72 a. The air blown from the scroll casing 72 is introduced into the evaporator 9 through the introduction duct 73, so that the introduction duct 73 works as another air passage.

[0042] A cross section of the air passage 72 a in the scroll casing 72 becomes gradually larger, as it goes from a nose 72 b (i.e., a volute tongue of the scroll casing 72) to an end of the scroll casing 72 so that the air in the air passage 72 a is effectively congregated (i.e., smoothly blown), and then the air is blown from the fan 71 toward the downstream side from the fan 71. In this embodiment, the cross section of the air passage 72 a is gradually increased along with a logarithmic spiral curve. Specifically, a scroll angle measured from the nose 72 b is along with the logarithmic spiral curve.

[0043] The introduction duct 73 includes an inner wall, all circumference of which is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passage. That is, the inner wall is smooth without any critical concavity or convexity on the inner wall. The inner wall includes an inside inner wall 73 a and an outside inner wall 73 b. The inside inner wall 73 a is continuously (i.e., smoothly) jointed to the nose 72 b, and can be displaced to a predetermined position so that the cross section of the air passage of the introduction duct 73 (i.e., the cross section of the duct 73) is changed in accordance with the airflow amount of the air blown from the scroll casing 72.

[0044] Specifically, the inside inner wall 73 a moves around the rotation axis of the fan 71, so that the air passage of the duct 73 is displaced between a maximum airflow position (shown as a solid line in FIG. 3) and a minimum airflow position (shown as a broken line in FIG. 3). Here, in case of the maximum airflow position, the amount of the airflow in the duct 73 becomes maximum, i.e., the cross section of the air passage of the duct 73 becomes large. In case of the minimum airflow position, the amount of the airflow in the duct 73 becomes minimum, i.e., the cross section of the air passage of the duct 73 becomes small. Thus, the inside inner wall 73 a works as a movable wall, which connects between the nose 72 b of the scroll casing 72 and a casing for accommodating the evaporator 9.

[0045] The outside inner wall 73 b faces the inside inner wall 73 a, and is disposed on the inner wall of the duct 73. The outside inner wall 73 b is smoothly jointed from the inner wall of the scroll casing 72, which is disposed on an outer periphery of the scroll casing 72. The outside inner wall 73 b is formed integrally with the scroll casing 72 and is made of resin.

[0046] A sliding portion between the inside inner wall 73 a and the scroll casing 72 and another sliding portion between the inside inner wall 73 a and the casing of the evaporator 9 are sealed with a packing as a sealing means for sealing the air from leakage. Specifically, the inside inner wall 73 a includes the first movable portion and the second movable portion. The first movable portion is disposed from the nose 72 b toward the scroll casing 72 so that the first movable portion provides a part of the scroll casing 72. The second movable portion is disposed from the nose 72 b toward the heat exchanger 9 so that the second movable portion provides a part of the introduction duct 73.

[0047] Next, the air blower unit 7 has characteristics described as follows.

[0048] As shown in FIG. 4, the applied voltage applied to the fan motor is increased so that the airflow amount of the air blowing from the fan 71 becomes larger. In this case, the inside inner wall 73 a is displaced toward a direction opposite to the outside inner wall 73 b so that the cross section of the duct 73 is increased.

[0049] As shown in FIG. 5, the applied voltage applied to the fan motor is decreased so that the airflow amount of the air blowing from the fan 71 becomes smaller. In this case, the inside inner wall 73 a is displaced toward the outside inner wall 73 b so that the cross section of the duct 73 is decreased.

[0050] Thus, both of the air passage in the duct 73 and the air passage 72 a in the scroll casing 72 can be optimized in accordance with the airflow amount.

[0051] Even when the inside inner wall 73 a is displaced, all circumference of the inner wall of the duct 73 is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passage. Therefore, no vortex is generated in the duct 73. Thus, a noise generated by the vortex of the airflow is reduced, and the air-blow amount of the air blowing from the air blower unit 7 is prevented from decreasing. Here, the decreasing of the air-blow amount is caused by a vortex loss of the vortex of the airflow.

[0052] Thus, the centrifugal air blower unit 7 has high air-blow efficiency and low air-blow noise.

[0053] (Second Embodiment)

[0054] A centrifugal air blower unit 207 according to a second embodiment of the present invention is shown in FIG. 6. The centrifugal air blower unit 207 includes an outside inner wall 273 b as a movable wall. The outside inner wall 273 b includes a movable inner wall 273 c disposed on the scroll casing side and another movable inner wall 273 d disposed on the evaporator side. A sliding portion 73 e between the movable inner walls 273 c, 273 d is sealed with a lip seal (i.e., a lip packing) as a sealing means for sealing the air from leakage. The lip seal is, for example, made of fluorocarbon rubber such as elastomer rubber, so that the lip seal is formed integrally with the movable inner walls 273 c, 273 d.

[0055] In FIG. 6, the maximum airflow position is shown as a solid line, and the minimum airflow position is shown as a broken line.

[0056] Thus, both of the air passage in the duct 73 and the air passage 72 a in the scroll casing 72 can be optimized in accordance with the air-blow amount. Even when the outside inner wall 273 b is displaced, all circumference of the inner wall of the duct 73 is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passage. Therefore, no vortex is generated in the duct 73. Thus, a noise generated by the vortex of the airflow is reduced, and the air-blow amount of the air blowing from the air blower unit is prevented from decreasing. Here, the decreasing of the air-blow amount is caused by a vortex loss of the vortex of the airflow.

[0057] Thus, the centrifugal air blower unit 207 has high air-blow efficiency and low air-blow noise.

[0058] (Third Embodiment)

[0059] In the air blower units 7, 207 shown in FIGS. 3 and 6, the movable inner walls 73 a, 273 c, 273 d are displaced in accordance with the applied voltage applied to the fan motor. In these cases, when the blower mode is switched, the air-blow resistance is also changed. Therefore, the actual air-blow amount is changed.

[0060] In view of the above point, in a centrifugal air blower unit 307 according to a third embodiment of the present invention, the movable inner walls 73 a, 273 c, 273 d are displaced in accordance with the blower mode (i.e., the operating condition of each blower mode switching door 18-20).

[0061] Specifically, in case of the face mode, the air-blow resistance becomes small so that the air-blow amount is increased. Therefore, the movable inner wall 73 a, 273 c, 273 d is displaced to the maximum airflow position. In case of the foot mode or the defroster mode, the air-blow resistance becomes large so that the air-blow amount is decreased. Therefore, the movable inner wall 73 a, 273 c, 273 d is displaced to the minimum airflow position. Here, in case of the bi-level mode, the air-blow resistance is moderate, so that the movable inner wall 73 a, 273 c, 273 d is displaced to a middle position between the maximum airflow position and the minimum airflow position.

[0062] Thus, both of the air passage in the duct 73 and the air passage 72 a in the scroll casing 72 can be optimized in accordance with the air-blow amount. Even when the movable inner wall 73 a, 273 c, 273 d is displaced, all circumference of the inner wall of the duct 73 is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passage. Therefore, no vortex is generated in the duct 73. Thus, a noise generated by the vortex of the airflow is reduced, and the air-blow amount of the air blowing from the air blower unit 307 is prevented from decreasing.

[0063] Thus, the centrifugal air blower unit 307 has high air-blow efficiency and low air-blow noise.

[0064] (Fourth Embodiment)

[0065] In case of an automatically controlled air conditioning apparatus, the ECU 21 controls the applied voltage applied to the fan motor and the blower mode on the basis of the target temperature TAO. Accordingly, in a centrifugal air blower unit 407 according to a fourth embodiment of the present invention, the movable inner walls 73 a, 273 c, 273 d are displaced in accordance with the target temperature TAO.

[0066] Specifically, when the target temperature TAO is set to be low, the air conditioning apparatus 1 operates in a cooling operation mode so that the blower mode becomes the face mode. When the target temperature TAO is set to be high, the air conditioning apparatus 1 operates in a heating operation mode so that the blower mode becomes the foot mode. Therefore, when the target temperature TAO is set to be lower than the first predetermined temperature, the movable inner wall 73 a, 273 c, 273 d is displaced to the maximum airflow position. When the target temperature TAO is set to be higher than the second predetermined temperature, the movable inner wall 73 a, 273 c, 273 d is displaced to the minimum airflow position. Here, the second predetermined temperature is higher than the first predetermined temperature. When the target temperature TAO is set to be in a range between the first predetermined temperature and the second predetermined temperature, the movable inner wall 73 a, 273 c, 273 d is displaced to the middle position between the maximum airflow position and the minimum airflow position in accordance with the target temperature TAO.

[0067] Thus, both of the air passage in the duct 73 and the air passage 72 a in the scroll casing 72 can be optimized in accordance with the air-blow amount. Even when the movable inner wall 73 a, 273 c, 273 d is displaced, all circumference of the inner wall of the duct 73 is continuously (i.e., smoothly) jointed from the upstream side to the downstream side of the air passage. Therefore, no vortex is generated in the duct 73. Thus, a noise generated by the vortex of the airflow is reduced, and the air-blow amount of the air blowing from the air blower unit 407 is prevented from decreasing.

[0068] Thus, the centrifugal air blower unit 407 has high air-blow efficiency and low air-blow noise.

[0069] (Modifications)

[0070] Although the air blower unit 7, 207, 307, 407 is applied to the air conditioning apparatus for the vehicle, the air blower unit 7, 207, 307, 407 can be used for another air conditioning apparatus for a ship, an airplane, and the like.

[0071] Although the movable inner walls 73 a, 273 c, 273 d are displaced with using a gear system or a link system, the movable inner walls 73 a, 273 c, 273 d can be displaced with using another driving means.

[0072] Although each movable inner wall 73 a, 273 c, 273 d has a certain shape shown in FIGS. 3 and 6, the movable inner walls 73 a, 273 c, 273 d can have another shape.

[0073] Further, the movable inner walls 73 a, 273 c, 273 d can be displaced in accordance with an airflow pressure detected by a pressure sensor. The airflow pressure is provided by the air-blow blown from the air blower unit 7, 207, 307, 407.

[0074] In the air conditioning apparatus 1 for the passenger compartment of the vehicle, the apparatus can includes a detector for detecting the airflow amount of the air blowing from the scroll casing 72 on the basis of an operating condition of the blower mode switching doors 18-20. In this case, the movable inner walls 73 a, 273 c, 273 d is displaced in accordance with the airflow amount detected by the detector.

[0075] In the automatically controlled air conditioning apparatus, the apparatus can includes a controller and a detector. The controller controls at least one of the blower mode of the air to be blown into the passenger compartment and the airflow amount of the air blowing from the centrifugal air blower unit 7, 207, 307, 407 on the basis of the target temperature TAO of the air to be blown into the compartment. The detector detects the airflow of the air blowing from the scroll casing 72 on the basis of the target temperature TAO. In this case, the movable inner walls 73 a, 273 c, 273 d is displaced in accordance with the target temperature TAO.

[0076] Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims. 

What is claimed is:
 1. A centrifugal air blower unit for blowing an air to a heat exchanger, the unit comprising: a centrifugal multi-blade fan having a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan; a scroll casing for accommodating the fan and for providing a first air passage so as to flow the air by an airflow amount; and an introduction duct having an inner wall for providing a second air passage, wherein the fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan, wherein the first air passage has a scroll shape and flows the air blown from the fan, wherein the second air passage introduces the air blown from the scroll casing toward the heat exchanger, wherein the inner wall of the introduction duct includes a movable portion, and wherein the inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion is displaced in accordance with the airflow amount of the air blown from the scroll casing.
 2. The unit according to claim 1, wherein each of the first and second passages includes an upstream side and a downstream side, and wherein the inner wall of the introduction duct is smoothly jointed from the upstream side to the downstream side of the first and second air passages.
 3. The unit according to claim 1, wherein the movable portion includes a seal for preventing an air leakage.
 4. A centrifugal air blower unit for blowing an air to a heat exchanger, the unit comprising: a centrifugal multi-blade fan having a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan; a scroll casing with a nose for accommodating the fan and for providing a first air passage so as to flow the air by an airflow amount; and an introduction duct having an inner wall for providing a second air passage, wherein the fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan, wherein the first air passage has a scroll shape and flows the air blown from the fan, wherein the second air passage introduces the air blown from the scroll casing toward the heat exchanger, wherein the inner wall of the introduction duct includes a movable portion, which connects to the nose of the scroll casing, and wherein the inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion of the inner wall of the introduction duct is displaced in accordance with the airflow amount of the air blown from the scroll casing.
 5. The unit according to claim 4, wherein each of the first and second passages includes an upstream side and a downstream side, and wherein the inner wall of the introduction duct is smoothly jointed from the upstream side to the downstream side of the first and second air passages.
 6. The unit according to claim 4, wherein the movable portion includes a first movable portion and a second movable portion, wherein the first movable portion is disposed from the nose toward the scroll casing so that the first movable portion provides a part of the scroll casing, and wherein the second movable portion is disposed from the nose toward the heat exchanger so that the second movable portion provides a part of the introduction duct.
 7. The unit according to claim 4, wherein the scroll casing includes a side wall, and wherein the first movable portion moves along with the sidewall of the scroll casing.
 8. A centrifugal air blower unit for blowing an air to a heat exchanger, the unit comprising: a centrifugal multi-blade fan having a rotation axis with an axial direction, an outer circumference and a plurality of blades disposed around the rotation axis of the fan; a scroll casing with an outer periphery for accommodating the fan and for providing a first air passage so as to flow the air by an airflow amount; and an introduction duct having an inner wall for providing a second air passage, wherein the fan sucks the air from the axial direction of the rotation axis and blows the air toward the outer circumference of the fan, wherein the first air passage has a scroll shape and flows the air blown from the fan, wherein the second air passage introduces the air blown from the scroll casing toward the heat exchanger, wherein the inner wall of the introduction duct includes a movable portion, which connects to the inner wall disposed at the outer periphery of the scroll casing, and wherein the inner wall of the introduction duct is smoothly jointed between the first and second air passages even when the movable portion of the inner wall of the introduction duct is displaced in accordance with the airflow amount of the air blown from the scroll casing.
 9. The unit according to claim 8, wherein each of the first and second passages includes an upstream side and a downstream side, and wherein the inner wall of the introduction duct is smoothly jointed from the upstream side to the downstream side of the first and second air passages.
 10. An air conditioning apparatus for a passenger compartment of a vehicle, the apparatus comprising: a centrifugal air blower unit according to claim 1; a blower mode switching device for switching a blower mode of the air to be blown into the passenger compartment; and a controller, wherein the controller controls the airflow amount of the air blowing from the scroll casing on the basis of an operating condition of the blower mode switching device.
 11. An automatically controlled air conditioning apparatus for a passenger compartment of a vehicle, the apparatus comprising: a centrifugal air blower unit according to claim 1; and a controller for calculating a target temperature of the air to be blown into the compartment and for controlling at least one of a blower mode of the air to be blown into the passenger compartment and an airflow amount of the air blowing from the centrifugal air blower unit on the basis of the target temperature, wherein the controller controls the airflow of the air blowing from the scroll casing on the basis of the target temperature. 